Note 9 - Disclosures About Fair Value of Assets and Liabilities - Fair Value of Assets Measured on Recurring Basis (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Available-for-sale securities	$ 83,205,195	$ 92,399,235
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	33,893,331	38,337,525
Corporate Debt Securities [Member]
Available-for-sale securities	3,070,000	7,053,522
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities	46,241,864	47,008,188
Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities
Fair Value, Inputs, Level 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities
Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities	83,205,000	92,399,000
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities	33,893,000	38,338,000
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Available-for-sale securities	3,070,000	7,053,000
Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities	46,242,000	47,008,000
Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities
Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Available-for-sale securities
Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available-for-sale securities
Interest Rate Swap [Member]
Interest rate swaps	151,420
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Interest rate swaps
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Interest rate swaps	151,000
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Interest rate swaps